A leader is not always identified by a “C” sewed onto the front of his uniform.

There is no such official designation signifying Landon Collins as a captain, but sometimes a player’s words and deeds are more impactful than the label assigned to him. Anyone who spent time Wednesday around Collins’ locker has to feel good about what the third-year safety brings to the team and what the future has in store for a 23-year-old with his head on straight.

With linebacker Jonathan Casillas on injured reserve, interim head coach Steve Spagnuolo made Damon “Snacks’’ Harrison the defensive team captain, a move no doubt based on Harrison’s seniority — though Harrison earlier this season stated he is not a leader. Moving forward, Collins will be a more suitable option.

Collins deftly diffused and shed light on the ongoing Eli Apple saga. Yes, Collins said, he has tried to get to Apple, the second-year cornerback whose career has taken a troubling downward turn — tactfully coming down hard on Apple while also offering unwavering support.

“We need him to be here. We need him to want to be here, and not fighting against us,” Collins said. “If he’s fighting against the coaches or the organization or whoever he’s fighting against in his head, we don’t need him fighting us, because that causes conflict.”

Collins said he and a few other Giants players have had “sit-downs’’ with Apple periodically throughout the season. “Multiple times,’’ Collins said. Veteran cornerback Dominique Rodgers-Cromartie expressed similar sentiment this week.

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Apple no longer is listed on the injury report — he had been dealing with a mild hip issue — and yet no one around the Giants can say with any certainty if he will play Sunday against the Eagles. Apple has not appeared in four consecutive games, and during Wednesday’s practice he worked with the second-team defense and the scout team, plus some reps on special teams.

“Trying to oil him back up,’’ Spagnuolo said. “We’ll see where he is at the end of the week. At the end, you got to make a decision on 46 players, so that’ll all unfold as the week goes.’’

Apple was benched at the start of the game with the Chargers for poor practice habits. He nearly walked out of the team facility after hearing pointed criticism of his play in San Francisco during a film session. Apple violated an NFL rule by tweeting during Sunday’s 30-10 loss to the Cowboys, and his retweet praising Rod Smith for his 81-yard touchdown against the Giants was particularly unnerving. Apple and Smith were teammates at Ohio State.

An NFL source said Apple is dealing with fallout from the divorce of his mother and stepfather, and also the recent brain surgery undergone by his mother.

“Down deep he’s a really good kid,’’ an NFL source, who has had dealings with Apple, told The Post. “He is just a young, entitled, immature kid. He’s 22, but he’s really like 16. Which is why he never should have gone with the 10th pick.’’

Apple and Dominique Rodgers-Cromartie at practice on Dec. 13Charles Wenzelberg/New York Post

Collins said: “He’s got a lot of personal things that’s going on in his life at this point. I’m surprised he’s still here and didn’t step away from the game, because most players would. He got a lot going on, and that’s when you have to be a brother towards him and tell him we got your back and we’re here for you.’’

Spagnuolo said Apple faces “some repercussions’’ for his tweeting during the game but was not willing to delve too deeply into what might be bothering the Giants’ 2016 first-round pick.

“I don’t want to pass judgment on a kid’s attitude or character,’’ Spagnuolo said. “I think that’s just between me and him, but the tweeting obviously was very disappointing. We got past that with an apology. We’re men. He’s a young man. … I’m into building up and not breaking down. So, we’ll keep trying to build up.’’

The ability to play the game, if he is practicing and playing like a professional, is not the issue with Apple.

“Oh, he has the most talent in the world,’’ Collins said. “Literally, he can do some amazing things. He already has a bad rep with the refs, other teams will tell the refs he holds and they will keep an eye out for him. Other than that, he’s a great cover corner, he understands the game, understands our concept of what we’re trying to put into the game.’’